Repositório Colecção:http://hdl.handle.net/10198/24872015-03-03T18:56:47Z2015-03-03T18:56:47ZFuzzy clustering for segmantation of 1st trimester ultrasound fetal imagesIgrejas, GetúlioSalgado, PauloCouto, Carloshttp://hdl.handle.net/10198/111042014-10-28T11:29:18Z2011-01-01T00:00:00ZTítulo: Fuzzy clustering for segmantation of 1st trimester ultrasound fetal images
Autor: Igrejas, Getúlio; Salgado, Paulo; Couto, Carlos
Resumo: The work herein presented is a part of a broader set of tasks included in a PhD thesis which main objective is to develop an automatic measurement system for the crown-rump, nuchal translucency and biparietal measurements in ultrasound fetal images. These measurements are of extreme importance to evaluate the possible abnormal conditions of the fetus, namely chromosomal anomalies like Down’s syndrome, also known as Trisomy 21. To achieve this objective the task of segmentation, which consists inidentifying the relevant objects/structures in the ultrasound images and separate them from the non relevant ones, is of utmost importance. In this work different fuzzy clustering approaches for segmenting 1st trimester ultrasound fetal images are presented and applied for the crown-rump measurement. Results are compared with other methodologies to evaluate their performance.2011-01-01T00:00:00ZClassification of alzheimer’s electroencephalograms using artificial neural networks and logistic regressionRodrigues, Pedro MiguelTeixeira, João PauloHornero, RobertoPoza, JesúsCarreres, Aliciahttp://hdl.handle.net/10198/110622014-10-27T14:54:34Z2011-01-01T00:00:00ZTítulo: Classification of alzheimer’s electroencephalograms using artificial neural networks and logistic regression
Autor: Rodrigues, Pedro Miguel; Teixeira, João Paulo; Hornero, Roberto; Poza, Jesús; Carreres, Alicia
Resumo: The Artificial Neural Networks have been used over the years to solve complex problems and their development has strongly grown in recent years. In particular, this work, focused on the development and a comparison between Artificial Neural Networks (ANN) and a traditional statistical technic known as Logistic Regression (LR) in Electroencephalogram (EEG) classification. The Wavelet Transform was seen as the main technique of signal processing, in order to analyze the EEG signals of this study. Some features were extracted by the EEG signals like relative power (RP) in conventional frequency bands and two spectral ratios. The best feature combination was selected by Principal Components Analysis method to increase the accuracy of the ANN and LR to discriminate their entries between Alzheimer Disease and Controls.2011-01-01T00:00:00ZOn the implementation of a microgrid project with renewable distributed generationLeite, V.Ferreira, Ângela P.Batista, J.http://hdl.handle.net/10198/109472014-10-23T01:00:43Z2013-01-01T00:00:00ZTítulo: On the implementation of a microgrid project with renewable distributed generation
Autor: Leite, V.; Ferreira, Ângela P.; Batista, J.
Resumo: This paper describes the on-going implementation of a microgrid project with renewable distributed generation under
the context of an initiative with demonstration purposes in an university campus. In the actual context of the electrical
energy demand increase and limited conventional resources, along with the consciousness of the climate changes and the
need to invest in clean energies, microgrids allows the integration of dispersed energy sources, mainly renewable, which
make them cost effective, providing a viable alternative to centralized production, transmission and distribution system for
remote community areas. The design concept of the microgrid and a description of the base equipment and energy sources
already integrated are presented. From the on-going projects to be integrated on the microgrid, it is presented the Grid-to-
Vehicle and Vehicle-to-Grid concept, which will provide a second energy storage element using the battery of an electric
vehicle. To accomplish this objective, a bi-directional power converter is being developed and simulation results of its
power structure and control are presented.2013-01-01T00:00:00ZAnálise do funcionamento do gerador de ímanes permanentes, com anisotropia inversa, isolado, alimentando uma carga resistivaFerreira, Ângela P.http://hdl.handle.net/10198/108902014-10-21T01:00:54Z2001-01-01T00:00:00ZTítulo: Análise do funcionamento do gerador de ímanes permanentes, com anisotropia inversa, isolado, alimentando uma carga resistiva
Autor: Ferreira, Ângela P.
Resumo: A utilização da máquina de ímanes permanentes como gerador isolado tem vindo a ser estimulada pelo aumento das potências disponíveis, através do desenvolvimento dos materiais magnéticos permanentes, nomeadamente nos últimos vinte anos, caracterizado pelo aparecimento das ligas de terras raras e por uma selecção adequada dos parâmetros da máquina. A análise do funcionamento do gerador de ímanes permanentes isolado, alimentando uma carga resistiva, baseada no modelo de Blondel simplificado, permite demonstrar uma vantagem funcional do circuito magnético anisotrópico inverso, sendo possível obter tensões superiores à força electromotriz induzida em vazio; estudos preditivos e experimentais permitem avaliar a dependência da regulação dos efeitos de saturação e da resistência do estator.2001-01-01T00:00:00Z